Mass Spectroscopy Chapters 7, 8, and 9

Mass Spectrum Diagram

Electron Source for Electron Ionization (EI) Ions travel to detector

Example of Fragmentation

EI and CI Comparison Electron Impact Ionization Chemical Ionization

Fast Atom Bombardment

What ions do the following mass represent? Analysis of Propene What ions do the following mass represent? 1) 42 m/z 41 m/z 42 m/z 2) 41 m/z 27 m/z 15 m/z 3) 27 m/z 4) 15 m/z

Analysis of 2-Methylhexane What ions do the following mass represent? 1) 100 m/z 43 m/z 2) 43 m/z 3) 41 m/z 85 m/z 41 m/z 100 m/z 4) 85 m/z

Useful Tables from Your Book pg. 260

Match Spectra with Compound Spectra A Spectra B Spectra A Spectra B

Match Spectra with Compound 1. 2. 43 m/z 55 m/z 71 m/z 85 m/z 42 m/z 84 m/z 3. 57 m/z 56 m/z Spectra 2 Spectra 1 41 m/z Spectra 3

Isopropylbenzene 105 m/z 120 m/z 77 m/z What ions are the following? Benzyl cation! 2) 77 m/z 1) 105 m/z

What is the likely Structure of the Following Aromatic Molecule? C10H14 119 m/z MW = 134 m/z MW = 134 m/z 77 m/z 119 m/z Why not ? 105 m/z

EI-MS of Triethylamine What is 86 m/z? 86 m/z MW =101 m/z (Notice odd #)

What is the Major Fragment? 58 m/z 58 m/z

Methyl 2-phenylethyl ether 45 m/z What is the ion corresponding to the following mass? 91 m/z 45 m/z 136 m/z What does 91 m/z correspond to?

Ethyl tert-pentyl ether What are the ions corresponding to the following masses? 87 m/z 1) 101 m/z 101 m/z 2) 87 m/z

What are the ions corresponding to the following masses? 3,3-Dimethyl-2-Butanol What are the ions corresponding to the following masses? 57 m/z 45 m/z 1) 45 m/z 87 m/z 102 m/z 2) 57 m/z 3) 87 m/z

Bromobenzene and Chlorobenzene 77 m/z 112 m/z 158 m/z 156 m/z 77 m/z 114 m/z MW 77 m/z appears on both spectra. What ion corresponds to 77 m/z? 77 m/z

1-halo-3-methylbutanes 43 m/z 43 m/z 70/71 m/z 70/71 m/z For all spectra, what ions corresponds to 71 m/z? What about 43 m/z? See if you can figure out the halogen for each spectra too! 43 m/z 71 m/z 43 m/z 71 m/z FYI: 70 m/z (loss of H from 71 m/z)

2-Heptanone 43 m/z 58 m/z 99 m/z 114 m/z What ions correspond to the following masses? (McLafferty Rearr.) 1) 43 m/z 2) 99 m/z 3) 58 m/z

5-methyl-2-hexanone 43 m/z 58 m/z 71 m/z 114 m/z What ions correspond to the following masses? (McLafferty Rearr.) 1) 43 m/z 2) 71 m/z 3) 58 m/z

Octanal 44 m/z 29 m/z What ions correspond to the following masses? (McLafferty Rearr.) 1) 29 m/z 2) 44 m/z

o-Methylbenzaldehyde 91/92 m/z 120/119 m/z What ions correspond to the following masses? 1) 92 m/z 2) 119 m/z

Octanoic Acid 60 m/z 73 m/z 101 m/z 115 m/z What ions correspond to the following masses? (McLafferty Rearr.) 1) 60 m/z 2) 73 m/z 3) 115 m/z

4-Ethylbenzoic Acid 105 m/z 150 m/z 135 m/z 76 m/z What ions correspond to the following masses? Even mass to even mass = 2 bonds broken! But not McL Rearr. 1) 105 m/z 2) 135 m/z 3) 76 m/z

Ethyl Hexanoate 88 m/z 99 m/z 60 m/z 73 m/z What ions correspond to the following masses? (McLafferty Rearr.) (McLafferty Rearr.) 4) 60 m/z 1) 99 m/z 2) 88 m/z 3) 73 m/z 4 bonds broken

Match the Constitutional Isomers (MW = 144) with their Mass Spectrums 102 m/z B 74 m/z 71 m/z 87 m/z B 74 m/z A 102 m/z

Match the Constitutional Isomers (MW = 143) with their Mass Spectrums 59 m/z B 87 m/z 72 m/z 100 m/z A 59 m/z B 87 m/z

Exact Mass of Common Elements

Find the Molecular Formulas from the Exact Mass 1. 137.1083 m/z C8H13N2 2. 99.0319 m/z C4H5NO2 3. 156.1510 m/z C10H20O

Determine the Structure of the Molecule Exact Mass: 106.0783 = C8H10 :p = 4 (4 rings/double bonds) 91 m/z 77 m/z 91 m/z 106 m/z 77 m/z 106 m/z